The present invention relates to apparatus and methods relating to signs suitable for outdoor use and with changeable message screens. More particularly, the invention relates to signs suitable for roadside and for providing messages viewable and readable at a distance of at least 200 feet.
Prior art changeable message signs with field changeable message screens suitable for roadside use have been cumbersome and expensive due to the conventional methods of constructing the signs.
Prior art exterior signs with changeable message screens have utilized a single large sign enclosure for framing and containing a matrix of changeable pixels which form the screen that displays the changeable message. The protection of the pixels, which are typically LED's and/or mechanically flipped fluorescent panels, as well as associated circuitry, is typically provided by the single large screen enclosure and an integral and unitary screen panel that is transparent or has transparent portions and which covers the entire screen. In the prior art signs the screen enclosure defines and limits the size of the message screen.
The circuitry for driving the pixels in these prior art signs is hardwired in a generally permanent fashion within the sign enclosure. Repairs or modifications to the sign screen is accomplished by accessing the internal circuitry and/or pixels by opening a door or panel. In many large highway signs an individual can walk into the enclosure for servicing the sign. In portable signs the access door typically includes the screen panel which is swung upwardly and propped open for working on the circuitry and/or pixels.
These prior art signs utilizing LED's and/or flip panels as the pixels may be constructed of a number of individual circuit boards with the LED's extending therefrom. The circuit boards are arranged in the desired message screen shape and size within the rigid steel sign enclosure. Typically, the sign controller will either connect independently through multiple conductors from the sign controller to each circuit board and associate LED's or there will be multiple ribbon cable and associated LED's or there will be multiple data lines in a daisy chain arrangement to each circuit board.
The sign enclosures are specifically sized for the desired message screen size. A sign controller, either within the screen enclosure or separately enclosed, operates to control the changeable message. Each of the circuit boards is assigned an address and the sign controller will typically utilize ribbon cable and connectors with multiple data conductors to send parallel data to the individual circuit boards for displaying the desired message. See U.S. Pat. No. 4,197,527 to Romney which discloses an outdoor modular sign. As in other prior art signs, Romney discloses the use of extensive cabling and wire harnesses for connecting to and providing control signals to the modules. Moreover, the modules in Romney, as in any other art outdoor signs utilizing modular circuit board arrangement of which the applicants are aware, are enclosed in a sign screen enclosure; thus the sign screen is not expandable. The support and mounting structure for the modules are thus sized for and typically part of such sign enclosures. Moreover any such mounting structure will typically provide only mechanical support for the mounting of the modules. Electrical connections are accomplished separately from the mechanical attachment to the sign enclosure and such electrical connections provide no mechanical support for the module.
As a result of the configurations of conventional prior art exterior changeable message signs, the pixel elements and the circuitry for the pixels are not serviceable from the front of the sign screen. Moreover, typically such prior art signs are not user serviceable and where such service is performed, the sign screen enclosure must be entered or opened thereby exposing all internal circuitry and pixel elements to the weather. This can cause difficulty in field servicing the sign screens particularly during rain or snow showers.
Much, if not the majority of the weight and bulk of traditional outdoor changeable message signs is in the screen enclosure. A breach of the enclosure, such as a crack or hole in the transparent screen panel subjects the entire screen circuitry and pixels to the elements, particularly moisture. Moreover, the size and weight of the screens necessitate heavy machinery, for example a crane, to install such signs.
Moreover, due to the massive weight, principally from the enclosure, dropping the changeable message screens can cause extensive damage to the sign screen or other property. Also, the significant bulk, weight, and rigid metal structure presents a hazard to personnel during the installation of such signs and to motorists who might collide with same.
Moreover, the weight and bulk of traditional outdoor changeable message signs requires a large and expensive support structure to support the enclosure. This of course increases the cost and labor for transportation and erection of such signs.
Moreover, the steel enclosures of the prior art outdoor changeable message signs often require ancillary cooling equipment. This of course, increases the weight, complexity, maintenance issues, and cost of the signs. Moreover, due to the size of the enclosures, effective weatherproofing was difficult. Hermetic sealing of such enclosures is generally impossible.
Thus, the prior art does not disclose an outdoor electronic message sign with characters viewable at a reasonable distance for reading, for example, at least 200 feet away, and which is easily changeable both with respect to the message and with respect to the screen size.
Conventional prior art exterior changeable signs are labor intensive and expensive to manufacture requiring fabrication of a steel screen enclosure, mounting of multiple boards with LED's or other pixel elements inside the steel enclosure, hardwiring of the components and connection to and enclosure of the sign controller. Typical lead time to manufacture such signs is four to five weeks.